Students already are familiar with the idea of polygons.
A brief description of the "hook" or activity:
Every pair of student is given two triangles that are similar but not congruent. They will cut them out and compare/contrast the two triangles. By overlapping the triangle's corners, they should be able to see that the size of the corners are the same, even though the triangles themselves are not the same.
Emphasize this idea of angle by asking students to take pieces of paper of different sizes, and then fold them twice until they get a right angle. Overlap the corners with their neighbors to verify that the square corners, or "right angles", will always be the same size. Allow kids to move around the room to find/share other examples of "right angles".
Then, project this video onto the board to 2:18 and ask them to guess what this tool is used for. Discuss its use to create right angles, and subsequently go to 2:38, 3:02, 3:56, 4:24, and 5:21 freeze frames to allow kids to describe the angles that they see. Are those angles bigger or smaller than "right angles"? Introduce the terms acute and obtuse then.
Links to worksheets, interactive widgets, etc (please be as complete as possible here):
Notes on using this lesson / suggested assessment / etc:
After this, pass out some tactile manipulatives (Geoboard, toothpicks, etc.) and ask students to build examples of right angles, acute angles, and obtuse angles. Or, alternatively, you can play Simon Says and ask the kids to use their arms as edges to create right, acute, and obtuse angles.
On the board, have ready a few different angles for the students to sort from smallest to largest.
As homework, assign kids to go home and find a magazine picture (or a picture online) of a building or another real-world object that has "acute" angles, and one that has "obtuse" angles.
Intro to Angles
Specific topic:
By the end of this lesson, students will be able to define an angle, and to be able to compare angles.Key terms:
Angle, vertex, greater, less, congruent, edge, right angle, acute angle, obtuse angle.Prerequisite knowledge:
Students already are familiar with the idea of polygons.A brief description of the "hook" or activity:
Every pair of student is given two triangles that are similar but not congruent. They will cut them out and compare/contrast the two triangles. By overlapping the triangle's corners, they should be able to see that the size of the corners are the same, even though the triangles themselves are not the same.Emphasize this idea of angle by asking students to take pieces of paper of different sizes, and then fold them twice until they get a right angle. Overlap the corners with their neighbors to verify that the square corners, or "right angles", will always be the same size. Allow kids to move around the room to find/share other examples of "right angles".
Then, project this video onto the board to 2:18 and ask them to guess what this tool is used for. Discuss its use to create right angles, and subsequently go to 2:38, 3:02, 3:56, 4:24, and 5:21 freeze frames to allow kids to describe the angles that they see. Are those angles bigger or smaller than "right angles"? Introduce the terms acute and obtuse then.
Links to worksheets, interactive widgets, etc (please be as complete as possible here):
Notes on using this lesson / suggested assessment / etc:
After this, pass out some tactile manipulatives (Geoboard, toothpicks, etc.) and ask students to build examples of right angles, acute angles, and obtuse angles. Or, alternatively, you can play Simon Says and ask the kids to use their arms as edges to create right, acute, and obtuse angles.On the board, have ready a few different angles for the students to sort from smallest to largest.
As homework, assign kids to go home and find a magazine picture (or a picture online) of a building or another real-world object that has "acute" angles, and one that has "obtuse" angles.
Credit sources, if any:
Using graphics from http://www.youtube.com/watch?v=MVLxXcfNWfE